Den hertog



Ar-E H 8- 7, 1951 M. DEN HERTOG 2,563,589

PULSE CONTROLLED RECTIFIER NETWORK Filed June 12, 1950 3 Sheets-Sheet l SOURCE OF w J IMPULSE SOURCE SYNCHRONIZED In vcninr MARTINI/5 new HEmvq By a a;

Attorney SYNCHRONIZOED Aug. 7, 1951 M. DEN HERTOG PULSE CONTROLLED RECTIFIER NETWORK Filed Jufie 12, 1950 s Sheets-Sheec 2 V2 JL v/ DELAY IMPULSE SOURCE OF v2 IMPULSE SOURCE SYCHRONIZED SYNCHRONIZE'D SYNCHRONIZED Inventor Attorney Aug. 7, 1951 M. DEN HERTOG 2,563,589

PULSE CONTROLLED RECTIFIER NETWORK Filed June 12, 1950 3 Sheets-Sheet 5 A/ 67 AW L In 5,20% A2 8'2 5:2 A3 5'3 A; 3 1 2 -v/ A 4 54 {1 5,50% A'5 8'5 AS 56 ADJU$TAB E 5 6 A 4 5, A DELAYL I 9' SZ\Z\\J(Q"2 27 l )1 1, 3 IMPULSE 1 Q/ Q 6 Q 5 Q 4 SOURCE a F2 2 Fb IMPULSE IMPULSE IMPULSE IMPULE SOURCE SOURCE SOURCE SOURCE SYNCHRONIZED SYNCHRONIZED Inventor MEET/NUS DEN HEFTOI;

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Patented Aug. 7, 1951 PULSE CONTROLLED RECTIFIER NETWORK Martinus den Hertog, Antwerp, Belgium, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application June 12, 1950,Serial No. 167,673 In France June 2, 1949 14 Claims. (Cl. 177-353) The present invention relates to a system of scanning electrical lines or equipments making it possible by static means to carry out a cyclic scanning of the electrical condition of circuits divided up into one or more groups in order to cause certain operation of selection, signalling or control, as also a system of comparison making it possible to employ the result of the scanning to effect said selection signallings or controls.

One feature of the invention comprises a system for selectively passing an electric signal from one of a number of individual electrical channels to a common electrical channel, said individual channels being multipled via a common point, said common channel being connected to different sources of potential, the potentials of which are capable of change from a normal absorbing value common to all sources to a blocking value common to all sources at different instants of time according to a predetermined cycle, whereby a signal potential applied to a channel is absorbed when the corresponding potential source has said absorbing value which is lower than said signal potential and transmits said signal potential to said common point when said potential source has said blocking value which is not substantially less than said signal potential.

Another feature of the invention comprises a system for selectively routing an electrical signal in any one of a predetermined plurality of diflerent time positions characterised by a plurality of individual channelswhich are equal in number to said time positions and which arev multipled in tree formation to a signal channel, diflerent potential sources being connected to said individual channels, the potentials of which are capable of change from a normal absorbing value common to all sai sources to a blocking value common to all as. d sources-at different instants of time, one per dividual channel, according to a Predetermined cycle, whereby a signal potential applied to said signal channel is absorbed in each individual channel in which the corresponding potentialsource has said absorbing value which is lower'than said signal potential and is effective on an individual channel only when the corresponding potential source has said blocking value.

Various other features will appear from the following description given as a non-limitative example, with reference to the attached drawings lines;

Fig. 2 shows a scanning device for an assembly of lines distributed into two groups; v

Fig. 3 shows a comparison device comprising two groups of control circuits; I

Fig. 4 shows a comparison device alternative to Fig. 3.

Fig. 1 shows an arrangement of circuit comprising three principal circuits EIB, EIB, E33, in

each of which are inserted a resistance R and a rectifier S. These circuits are connected in parallel to the point B, the object of rectiflers SI to 83 being to prevent current from flowing between the terminals E when the potential of one of them The terminals El to E3 are connected to the circuits to be scanned which can apply said terminals either to potential ,Vl or to potential V2,'as indicated. 'There is connected to each of the scanning circuits a shunt circuit Al, Pl; A2, F2; A3, F3, in which are inserted the rectifiers Ql Q2, Q3. The terminals El, F2 and F3 are respectively connected to three sources of impulses l, 2, and 3 which cause their potential to vary from VI to V2, at the same frequency, but in time units which have been assumed to be staggered by a third of a period in time, as indicated by the wave forms adjacent the connecting leads.

when the potentlal of the terminal El has the value VI and that of terminal Fl the value V2, V2 being greater than Vl, the rectifier Ql is not conductive and the point Al remains at the potential Vl; when the potential of the terminal El has the value'VI and that of the terminal Fl the value Vl, the rectifier Ql is conductive and current flows from the generator connected to terminal El to the generator connected to terminal Fl This current flow causes a drop of potential in the resistance Rl; by judicious choice of the value of this resistance, taking into consideration the value of the other elements of the circuits, it is possible to obtain that the potential of the point Al is maintained at the value Vl. When, at the same time the terminals El and El are applied to the potential V2, the point Al is brought to this potential. In the same way, the points A2 and A3 will be brought to the potential V! when said potential is simultaneously received on the terminals E2, F2 and E3, F3.

The point B will be brought to the potential V! Fig. 1 shows a scanning device for a group of of said lines.

We thus get an actual successive and repeated scanning of the lines associated with the terminals El, E2, E3.

- By increasing the number of periodic impulse sources and consequently dephasing them with respect to each other in order only to have a single impulse at a given moment, it is possible to increase the number of lines scanned, each impulse source being allocated to a particular line.

potential V2 applied to the terminal E4 is returned to the point B2, said point B2 is at a higher potential than the terminal F112 and the rectifier Q'2 is conductive. Current will flow from the source connected to E4 into the source b2 connected to EN, causing in resistance R4, a drop of potential which lowers the potential of point B2 to the value VI. The indication of the electrical condition of terminal E4 will not then be sent to point C. 1

It is clear that it is thus possible successively to receive on the point C the indication of the electrical condition of the six terminals E. For example, by using sources of short impulses staggered in time, the 10 sources of long impulses staggered in time of which the duration of each impulse would be equal to the duration of the The method which has just beendescribed limited, when the number of lines tobe scanned increases, by the number of different sources of current which can be used in practice.

The arrangement of Fig. 2 makes it possible to scan a large number of circuits with a number of sources of current which is lower than the number of circuits. It has been assumed, as an example, that the six scanning circuits were distributed into two primary groups identical with that of Fig. 1, of which the output circuits B1 and B2 are connected to a common point C, each of them through rectifiers Sl and S'2, respectively. The points BI and B2 are respectively connected to the terminals Fbl and FM through the rectifiers Q'l and QZ. The terminals Fbl and F122 are connected respectively to impulse sources bl and b2 peculiar to each of them; the duration of the impulses producedby 'each of these sources is equal to one cycle of successive impulses of short duration of each of the sources al, a2, and all connected to terminals Fal, Fa2, Fall. I

Moreover, the long impulses of the two sources bl and ,b2 connected to Fbl and FM are successive in time, that is to say, that at a given moment, only one of the sources transmits an impulse. The duration of a cycle of two long successive impulses from bl and b2 is equal to the duration of two successive cycles of short impulses from al, a2 and a3. Each of the sources bl, b2 of slow impulses characterises one of the two primary groups.

If the sources of long impulses had not been connected to the points BI and B2, a short irripulse received on the terminal Fal, for example, would as explained for Fig. 1, cause the simultaneous appearance at BI and B2 ofan impulse V2 if the two terminals El and E4 were at said potential V2. The points BI and B2 being connected at Fbl and PM, via the rectifiers Ql and Q2, the simultaneous appearance of an impulse FM is at potential VI {ow ng tothe' factthatthe cycle on a succession of short impulses, it would be possible to scan a 100 terminals E divided up into 10 primary groups of 10 terminals.

The rectifiers S'l and S'2 are provided in order to prevent the lowest potential Vl received on one of the points Bl or B2 from influencing the highest potential V2 received simultaneously on the other of said points Blflor B2;

From the foregoing, itis clear that the scanning device causes the appearance,'at its output point, successively of the electrical conditions of the lines which it is scanning; In an automatic telephone system for example, it is possible in this way to obtain the condition of each of the outlets which give its class, the group to which it belongs, whether it is free or busy, whether it is calling or not calling. These conditions are characterised by the presence of a particular potential in a particular time unit.

It is obvious that the number of scanning circuits per group and the number of groups can be increased by employing the impulses of short and of long duration which would be necessary.

These electrical conditions can then be compared with the electrical condition required in order to proceed with certain selection, signalling or control operations. In order to make this comparison and initiate the selection, signalling or control operations, it is possible, for example, to employ one of the means described in the patent applications filed to the present applicant on May 24, 1949, in France, for Selection system for electrical circuits or equipments, No. 572,854 and No. 572,855.

It is also possible to use the device of Fig. 3 as comparator.

When no impulse is received on the input terminal C, the potential of said terminal has the value Vl. Under these conditions the potential applied to the terminals E l to ES' is maintained 'at the value Vl. Let us, for example, consider the circuit connected to terminal E I. If impulse V2 from the sources al and bl, respectively, are simultaneously received on terminal F'al and ,F'bl, the'source V2 connected to terminal BG will discharge into the source connected to they point C owing to the fact that the potential of the point F'l being higher than that of the point C, the rectifiers S'l and Sbl are conductive. The drop of potential in resistance R'l maintains the point Fl and consequently the terminal El at a potential Vl.

;If an impulse V2 is received on the terminal C, he terminal E. of the circuit connected to the sources which-give in the same time unit a poten- 'ftialVZ will belbrought, to said potential V2. The other terminals E willremain at potential VI.

Let us. for example, consider the circuit connected asaaseo to terminal E'l. If, when impulse V2 is received on the terminal vC, an impulse V2 is received at point A'l from the source al connected to terminal F'al, but no impulse is received at point B'l coming from the terminal F'bl the source of potential V2 connected to the terminal BG, will discharge in the source bl connected to the terminal F'bl, said terminal being at the moment under consideration at the potential Vi. Point F'l will be kept at potential VI on account of the drop of potential in resistance R l. The potential V2 of terminal C cannot be received on terminal E'l owing to the orientation of rectifier S'bl. Similarly, if the potential V2 were received on the terminal F'bl, the terminal Fal being at potential VI, the point F I will be maintained at the potential VI on account of the flow of current from terminal BG to terminal F'al. If, on the other hand, a potential impulse V2 is simultaneously received on terminal F'a I, F'bl and C there can be no flow of current and the potential V2 of the source connected to terminal BG is applied to terminal E'l.

It is clear that it i thus possible to apply potential V2 to only one of the terminals E at a given moment, said terminal depending on the position in time of the impulse V2 received on terminal C. The potential V2 received on the terminals E may be employed to produce any desired control or signalling by adjusting its time position.

It is obvious that the capacity of the comparator can be increased by increasing either the number of secondary comparison circuits of each of the groups or by increasing the number of groups and by employing the impulses of short and long duration which would be necessary.

Referring now to Fig. 4, first of all, we will consider only the circuits Er, E: and E's and it will be assumed that the points A1, A: and A: have been respectively connected to the terminals F'al, Fa2 and Fa3 but that the points LB'1, B's and B: have not been connected to the terminal F'bi. when no control impulse is received on the input terminal C of the comparator the said terminal is at a potential V1 which is received on the terminals E'i, E'r, E's; said potential V1 cannot cause an order. when an impulse of potential V: is received on one of the terminals F'ar, F'az, Fas, from sources al, (12, or 03, respectively, if at the same instant the point C' is at the potential V1. the point A'i, A: or A: is at a potential lower than that of the terminal F'a, and owing to their orientation, the rectifiers Q'1, Q'3, Q's are not conductive and the point A'1, A's, or A: is maintained at the potential V1. It would be assumed that an impulse of potential Va is received on the terminal 0, the potential of the terminal F'al being at V1. The potential or the point A'i being in this case higher than that oi! the terminal F'al the rectifier Q'l is conductive,

and current can flow from the source connected to the terminal 0' into the source all connected to the terminal F'al. This flow of current produces a drop of potential in the resistance R1 of which the value is chosen, taking into consideration the other elements of the circuit, so that the potential of the point Ai, and consequently of E'1, is maintained at the value V1. If, on the other hand, an impulseVz is simultaneously received on the terminal C and on the terminal F'ai, there will be no flow or current through the rectifier Qr owing to the fact that the point All and the terminal F'ar are at the same potential. 'lhepotentialVawillinthiscasabereceivedon 9. drop of potential which maintains the point B's 6 the terminal E'i and will cause the desired control or signalling.

Owing to the fact that the impulses of potential V2 are received in diflerent time units on the terminals Fai, F'aa and F'G3, from sources al, a2 and a3, respectively, the result is; that upon reception of an impulse V2 on the terminal C, only one of the terminals E1, E: or E: will be brought to the potential V2; the said terminal will be that of the comparison circuit of which the impulses received on the shunt circuit has the same position in time as that received on the terminal C.

It is obvious that without departing from the scope of the invention it would be, possible to increase the number of comparison circuits by providing as many sources of potential impulses as of comparison circuits, the impulses of the different sources being situated in different time We will now explain the operation of the whole of the devices of Fig. 4.

It has been assumed by way of example that the comparator device was made up of two groups of three comparison circuits. The circuits E'1 and E4 are connected to the same terminal F'al through a rectifier Q'i and Q: peculiar to each of them. Similarly the circuits E: and E's are connected to the terminal Faz and the circuits E: and E's to the terminals Fas. Moreover the points 3'1, 3'2 and B's of the three circuits of the first group are connected through the individual rectifiers Q1, Q"z and Q": to the terminal Flu, and the points 3'4, 3'5 and B's are connected through the individual rectifiers Q"4, Q"s and Q"s to the terminal F'bz. The said terminals F'ln and F'bz are connected respectively to two special impulse sources bl and b2. The duration of the impulses from these sources is equal to the duration of one cycle situated in time of each of the impulses from the sources at to a3 connected respectively to terminal For. to Faa. For example, during the reception of a potential impulse on the terminal F'bl, a potential impulse will be successively received in each of the terminals F'ar, Far, and Fas. Moreover the cycle of impulses from the sources bl and b2 connected respectively to terminals Fbi and Fbz is provided so that at a particular moment only a single potential impulse is received from one or other of the sources.

From the above explanations it will be seen that in order that the control potential V2 may be receiveid on a terminal E, it is necessary for said potential to be simultaneously received on the terminals C, F22 and F'a. If, for example, at

a particular moment potential V: is received on the terminals C, F'br and F'al, said potential will 'be transmitted to the terminal E'1, the sources aland a2 connected to Far and F'b1 not being open. On the other hand, the potential V: will not be received on the terminal, E'4. In fact, it being given that, at the moment under consideration, the terminal Fln is at the potential V2, the result is that the terminal Fbz is at potential V1. The source b2 connected to Fbz absorbs the potential V: sentfrom C'1 on the circuit of terminal E'l and causes in the resistance R's at the potential V1.

It is clear that under'these conditions, 'at a given moment, only one group g g comparison cirouitsis in a condition to cause the control potential to appear on' the output or one of these comparison circuits. It is therefore possible by this method to obtain a single order on an assembly, of circuits distributed in'groups with a aseasao number of impulse sources lower than the total number of comparison circuits of the whole of the groups.

It is, of course, obvious that it would be possible without departing from the scope of the invention to increase capacity of the comparator either by increasing the number of comparison circuits in each of the groups, or by increasing the numberof groups, or by combining the groups together and employing the impulse sources of diiffierent durations and predetermined position in time which would be necessary.

I claim:

1. An electrical channel scanning system comprising a plurality of first electrical channels, a second electrical channel, circuits for connecting said first channels in multiple to said second channel, a common reference terminal, a plurality of sources of electrical pulse trains of equal repetition rate; the, pulses of eachtrain having a shorter time durationthan 'theitinie displacement betweenpulses andz the pulses of. each train having a different, tirneixpositionz with respect to the pulses of. any other 't'rainfmeans including a plurality of rectifiers for connecting said sources of pulse trains respectively between said common reference terminal and points ofsaid first electrical channels, there being one rectifier for'each first channeland the rectifiers being so poled that the application of a pulse from an associated source will block current flow though the rectifier, means for selectively applying a signal potential having a value at least as great as the value of said pulses between said common reference terminal and one of said channels, a plurality of resistances associated respectively with said circuits in such a manner that any current flowing through a rectifier will pass through the associated resistance, and means for blocking current flow between said first channels.

2. A scanning system, according to claim 1, in which the means for applying a signal potential to a channel is means for applying constant signal potentials to one or more of the first channels.

3. A scanning system, according to claim 2, in which the resistances are included in the circuits between the means for connecting the pulse train sources and the means for applying the signal potentials.

4. A scanning system, according to claim 3, in which the means for blocking current flow between the first channels are rectifiers, one connected in each connecting circuit adjacent the second channel and poled so as to permit current to flow towards said second channel.

5. A scanning system, according to claim 1, in which the connecting circuits are divided into groups with the circuits of each group connected together and additional connecting circuits'are provided connecting said groups to the second channel, and in which said system further comprises additional sources of pulse trains, one for each group of circuits, the pulses of each additional source having equal repetition rates, the said repetition rate being a sub-multiple of the repetition 'rate of the first-mentioned pulse trains, and each pulse having a time duration equal to a complete cycle of said first-mentioned pulse trains, with the pulses of each additional train having a different time position from that of the pulses of any other additional pulse train, and means for connecting each of said additional pulse train sources between the reference ter minal and respective additional connecting circuits, said means including individual rectifiers for each circuit poled similarly to the first-mentioned rectifiers.

6. A scanning system, according to claim 5. in which the means for applying a signal potential to a channel is means for applying. constant signal potentials to one or more of the first channels, and in which the resistances are included in the circuits between the means for connecting the pulse train sources and the means for applying the signal potentials.

7. A scanning system, according to claim 6, in which the means for blocking current flow between the first channels are rectifiers, one connected in each connecting circuit adjacent the second channel and poled so as to permit current to flow towards said second channel.

8. A scanning system, according to claim 1, further comprising means for applying a potential at least as great as the potential of the pulses between the common reference terminal and all of the first channels through the resistances associated with said channels, and in which means for applying the signal potential applies said potential to the second channel.

9. A scanning system, according to claim 8, in which the connecting circuits are divided into groups with the circuits of each group connected together and additional connecting circuits are provided connecting said groups to the second channel, and further comprising additional sources of pulse trains, one for each group of circuits, the pulses of each additional source having equal repetition rates, the repetition rate being a sub-multiple of the repetition rate of the first-mentioned pulse trains, and each pulse having a time duration equal to a complete cycle of said first'mcntioned pulse trains, with the pulses of each additional train having a different time position from that of the pulses of any other additional pulse train, and means for connecting each of said additional pulse train sources between the reference terminal and respective additional connecting circuits, said means including individual rectifiers for each circuit poled similarly to the first-mentioned rectifiers.

10. A scanning system, according to claim 9,

in which the means for applying a signal potential to a channel is a means for applying a pulse train to the second channel.

11. A scanning system, according to claim 10, in which the means for blocking current flow between the first channel are rectifiers, one connected in each connecting circuit adjacent the second channel and poled so as to permit current to flow towards said second channel.

12. A scanning system, according to claim 11, in which means for applying the constant potential to the first channels comprises individual connections to said channels including the resistances. l

13. A scanning system, according to claim 1, in which the resistances are connected respectively in the connecting circuits adjacent the second channel and in which the means for applyling a signal potential to a channel is means for applying a pulse train to the second channel.

14. A scanning system, according to claim 13, in which the connecting circuits are divided into groups with corresponding circuits of each group connected through individual rectifiers to a source of pulse trains whi h is different from the source of pulse trains connected to the other corresponding circuits of each group, and further comprising additional sources of pulse trains, there being one for each group of circuits, the

. guano I I l 10 pulses of each additional source having equal rectifier: for each circuit poled similarly to the repetition rates, each repetition rate heinz a mat-mentioned rectiiiers. the means for blocksub-multiple o! the repetition rate 0! the firsting current iiow between said first channels commentioned pulse trains. and each pulse having a prising the rectiiiere over which said pulse trains time duration equal to a complete cycle of said a are connectedtoaaid first channels.

first-mentioned pulse trains, with the pulses of MAR'I'INUB our HERTOG. each additional train havin: a different time position from that o! the pulses a! any other REFERENCES CITED ddi o P l tr and mm m- The following references are of record in th in: each oi-said additional pulse train's ources' 10 m t i mm: e betweentherei'erenceterminaiandallthecire rnm F 1949 cuitsotali'ounsaidmesnsincludinzindividual 

